Jim Sims

Making genetic genealogy more understandable...

S1. Upload raw data (free to use)
(Updated 25 Jul 2019)

GEDmatch completed the process of migrating all of its autosomal DNA database to a new format in June of 2019 so that there is now only one such database. It is called GEDmatch. Previously, there were two databases, one called GEDmatch and one called GEDmatch Genesis. This required two web sites. Now there is only one web site for GEDmatch. The reason GEDmatch Genesis was created was in response to changes in DNA chip technology some vendors of DNA testing services adopted several years ago.

If you need help downloading raw autosomal data from the vendor you tested with, see this tutorial.

1. Log-in to your account at GEDmatch. In June 2019. Locate the upload area on right side of your GEDmatch home page:


2. Begin by using the first upload option: Generic Uploads shown in the graphic above. This will take you to a page you use to provide information about the autosomal raw data you will upload. This includes(a) naming the donor or providing an alias, (b) haplogroup information if known, (c) the name of the DNA testing company, (d) your relationship and permission that allows you to upload the raw autosomal data, (e) who may see matches with the kit created with this raw autosomal data. At the bottom of the page, see graphic below, is a Botton "Choose file" that you can use to locate the raw autosomal database on your computer's hard drive. Once the file has been selected, click the upload button. Be sure to wait for the upload process to complete.


Once you upload the raw data, it make take several days for the information to be processed and added to the GEDmatch database.

S2. Find matches with the One-to-Many DNA Comparison Result tool (free to use)
(Updated 25 Jul 2019)

1. Log-in to your account at GEDmatch. On the home page, locate the DNA applications area on the right side of the page:


2. Click on the link for the One-To-Many DNA Comparison Result tool (see red box in image above).

3. Then enter the kit you would like to compare to other kits in the GEDmatch database:


4. Next, click the Display Results button (shown in the graphic above). The compare results will be shown on a page similar to the one shown in the graphic above. Kit numbers, names and email addresses have been blurred for privacy. The results are sorted by Total cM with matches sharing the most DNA at the top of the page. Note: You should not contact people identified as matches using this tool without first confirming the match with the One-to-One Compare tool. See S3 below for this procedure


S3. Confirm a match with the One-to-One Comparison tool
(Updated 25 Jul 2019)

1. The easiest way to confirm a DNA match tentatively identified with the One-to-Many tool in S2 above, is to click the "A" link on the row of interest on the One-to-Many results page. The "A" link is found in the column labeled 1:1 in the graphic above. This is the second column from the left. If you click the link, it will take you to the data entry page for the One-to-One Compare tool and populate the kit number fields for you. The other method is to write down the kit number of interest, and choose the One-to-One Autosomal DNA Comparison tool from among the DNA applications on the GEDmatch home page.


2. Accept most of the default parameters. Do check the box to prevent hard breaks shown boxed in red in the graphic above. Then click the Submit button.

3. At the top of the results page for the comparison will be a legend explaining the meaning of the colors shown in the graphics on the page:


With the exception of the comparisons of full and 3/4 siblings, the areas of interest on the results page will be areas primarily colored yellow (meaning a half identical region) with a blue bar below the area on the chromosome, such as shown like this:


To read the result for chromosome 10 shown above, it says there is a half-identical DNA match of 28.0 cM beginning at approximately 25.47 megabases (from the left end of the chromosome), which ends at approximately 61.9 megabases containing 7,073 SNPs (pronounced snips). The blue bar shows the region on the chromosome that meets the matching criteria. The shading above the blue bar is primarily yellow in color, indicating a half-identical region. Recall that each person in the comparison has two copies of chromosome 10. Half-identical means a match on only one of the pair of chromosomes for each person.

It is possible that some matches identified by the One-to-Many tool will fail to show a match with the One-to-One tools. These are typically low cM matches identified with the One-to-Many tool. When this occurs, the match identified with the One-to-Many tool was a false positive match. You should ignore false positive matches.

S4. Analyze matches with the 3D Chromosome Browser (free to use)
(Updated 25 Jul 2019)

1. Log-in to your account at GEDmatch. Use the DNA application area on your home page (see graphic in S2 above) and click on the 3D Chromosome Browser link to navigate to this tool. You will be presented with a data entry form similar to this one:


2. Don't change the cM threshold value of 7. Click the Display Results button after entering the kit numbers.

This tool will display data in several tables that shows how up to 10 people share DNA. After presenting the tables, there is a button to view the chromosome browser. In this example, only one of the tables is shown based on the data entry form above:


In this example, the author's kit is kit A. He shares DNA with kit H and kit Z. H is the author's half 2nd cousin (H2C). H shares DNA with A, T and M. T and M share a small amount of DNA according to this tool. The dashes in the table show a kit compared to itself and are of no interest.

S5. Find triangulated segment matches with the Triangulation tool (paid subscription required)
(Updated 25 Jul 2019)

DNA segment triangulation refers to trios of people who share DNA on the same chromosome at the same or overlapping locations. When matches of this type occur, one can be more confident that all three people in the segment triangulation inherited the DNA segment by common descent from an ancestor or ancestral couple. This is a more detailed kind of chromosome comparison than that performed in most chromosome browsers. It should be noted that the chromosome browser at MyHeritage will show triangulations when present, but you can't search for triangulated segments at MyHeritage.

1. Log-in to your kit at GEDmatch.

2. Locate the Tier 1 area showing the subscription-based tools, and click the link for the Triangulation tool (see red box in graphic below):


3. Enter the kit number of interest on the data entry form for the Triangulation tool. Accept all of the default settings, then click the Submit button at the bottom of the page:


The results table looks similar to the graphic below:


Each row shows a segment triangulation between the kit number that was entered in the data entry form and two additional kits in the GEDmatch database. In this example, the author has a triangulated DNA segment with kit A7 and kit M4. This is located on chromosome 1 beginning at approximately 13.8 megabases and ending at approximately 38,9 megabases. The segment has a cM value of 38.7. The green graphic in the right most column helps you see the overlap in triangulated segments and you scroll down through the rows of the result table.

In this example, the author has a triangulated segment on the second row of the table with kits M4 and KP beginning about 14.8 megabases and ending at about 38.9 megabases. The segment has a cM value of 36.1. This triangulated segment overlaps the segment on row one of the table. When this occurs, one can be more confident that the all people in these two triangulations share this DNA segment due to common descent from an ancestor or ancestral couple.

4. Scroll to the bottom of the page and download the results for study off-line (see HERE link in the graphic below):


A tab separated file can be opened with a variety of software including spreadsheets and databases.

This site does not collect information about visitors. By clicking on a link to another web site, that site might track you, but this site does not. This site has no business or commission arrangements with other web sites.